new MosFETs on the block...

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Since Infineon has now pushed its OptiMOS series up to 200 and 250V, there seems to be a new high performance 200V MosFET:

Infineon IPP110N20N3 200V 11mOhm, gate charge only 65nC (looks like a new world record for TO220)

i guess it could be well used for half and full bridges up to ~ 180V.

For even higher bus voltages there is a 250V 20mOhm FET too...

(no I m not an infineon sales guy, but I am always curious whats new on the market since I still have an unfinished class D project ongoing)

anybody has experience with these parts or is considering to use them, e. g. instead of IRFP4668 or the like?
 
Looks nice, but the miller capacitance of just 5pF must be a typo

..looks like they specifiy this kind of low miller C throughout the series (just look at IPP200N25N3, IPP320N20N3 and so on...).
looking back at their track record, it wouldn't be the first time in history for Infineon to be miles ahead of their competitors in terms of innovation.. hmm..
..i think i ll try to get my hands on some samples..
 
Capacitances always need be referenced to some voltage:
5 pF @ 60V, but
200 pF @ 10V
and then some...
That's the price for high transconductance/low Ron and high current capability.
 

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Most ringing problems in class D output stages arise from series resonance between the output capacitance of the MOSFET that is turned off and with high Vds, and all package and layout inductances (the MOSFET that is on and supply decoupling capacitors are closing the circuit). Snubbers are often required to damp this resonance to a reasonable degree.

200pF at 10V is nothing to worry about, and 5pF at 150V with a good layout will resonate at such a high frequency that snubbers won't have anything to damp (above 100Mhz non-RF-specific circuits tend to be self damped due to high losses). Snubbers are probably still required, but just to control dV/dt at the switching node in the voltage transition that happens after body diode recovery.

Interestingly, Infineon does not mention dv/dt and di/dt strength of the body diodes, at least not for IPP110N20N3. But IR neither mentions this data in IRFB4227 datasheet, yet they have proven to be very reliable below 750A/us, 15V/ns and 40A.

EDIT: With these MOSFET, due to the low capacitance, amplifiers with extremely low dead time and idle losses can be made.
 
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Most ringing problems in class D output stages arise from series resonance between the output capacitance of the MOSFET that is turned off and with high Vds, and all package and layout inductances (the MOSFET that is on and supply decoupling capacitors are closing the circuit). Snubbers are often required to damp this resonance to a reasonable degree.

200pF at 10V is nothing to worry about, and 5pF at 150V with a good layout will resonate at such a high frequency that snubbers won't have anything to damp (above 100Mhz non-RF-specific circuits tend to be self damped due to high losses). Snubbers are probably still required, but just to control dV/dt at the switching node in the voltage transition that happens after body diode recovery.

Interestingly, Infineon does not mention dv/dt and di/dt strength of the body diodes, at least not for IPP110N20N3. But IR neither mentions this data in IRFB4227 datasheet, yet they have proven to be very reliable below 750A/us, 15V/ns and 40A.

Eva, are you effectively using the slow body diodes of IRFB4227. Body diode dv dt capability is only an issue if the body diode is hard recovered from a conducting state. Based on what I 've heard, at this voltage level its quite wise to use external freewheeling instead of slow high Qrr body diode thus saving reverse recovery losses at the expense of series diodes in the drain path and its losses. The new Infineon part is worse in therms of its internal diode...
 
IRFB4227 body diodes are not slow at all. In one of my circuits a pair of them fully recovers from 80A conduction in 80ns.This is not worse than an ultrafast diode, but without consuming extra space or heatsink area, and benefiting from Rds-on shunting the diode most of the time.

With the Infineon part and proper drive, Rds-on (.01r) would prevent body diode conduction almost completely.
 
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IRFB4227 body diodes are not slow at all. In one of my circuits a pair of them fully recovers from 80A conduction in 80ns.This is not worse than an ultrafast diode, but without consuming extra space or heatsink area, and benefiting from Rds-on shunting the diode most of the time.

With the Infineon part and proper drive, Rds-on (.01r) would prevent body diode conduction almost completely.

ok slow or fast is relative. I mean in comparison to Vishay 200V schottky they are still slow.
 
What you fail to understand is that with external diode there is always a diode recovery process taking place, and conduction losses are increased substantially. On the other hand, with Rds-on shunting the diode, reverse recovery only happens during high current peaks when driving low impedances, and only for the amount of current that the diode is shunting from Rds-on, not for the full current. The amplifier I mentioned can do full power into 4 ohm without diode recovery, which is only required for 2 ohm operation.

In terms of efficiency (power efficiency, cost efficiency, space efficiency), the Rds-on shunting method wins with current state of the art 200V and 250V MOSFET. For 500V/600V I would still go for external diodes or IGBT.
 
What you fail to understand is that with external diode there is always a diode recovery process taking place, and conduction losses are increased substantially. On the other hand, with Rds-on shunting the diode, reverse recovery only happens during high current peaks when driving low impedances, and only for the amount of current that the diode is shunting from Rds-on, not for the full current. The amplifier I mentioned can do full power into 4 ohm without diode recovery, which is only required for 2 ohm operation.

In terms of efficiency (power efficiency, cost efficiency, space efficiency), the Rds-on shunting method wins with current state of the art 200V and 250V MOSFET. For 500V/600V I would still go for external diodes or IGBT.

I see. But isn t there a risk of thermal runaway? Hotter FET means more RDSon means higher percentage of peak current in the body diode means more recovery losses means more temp means more RDSon... you get the idea..

I think the hypex UCD2k does have external diodes - don't kill me if I am wrong..
 
Diode forward and reverse recovery processes are symmetrical. The charge that takes 100ns to be removed from the diode took another 100ns to be stored... Oh, wait, was the diode allowed to conduct full output current for so long? Obviously no.

Damn, hasn't nobody learned this by investigating and optimizing bipolar transistor switching circuits before going into MOSFET?

UCD2k is not as advanced as the lower power versions, yes, it has external diodes. It seems that they are much more creative for small signal stuff than for KW power switching.

Optimizing switching timing only makes sense when it's the major source of non linearity, once the modulator becomes the dominant source of distortion, it's pointless (without improving the modulator too).

I don't want to advertise directly the product where my amplifier module is being used, but IR2110 timing is good enough to require no trimming at all (+/-10ns). Consistency between units is very good, there are a few hundred modules working out there now without problems. Idle losses are substantially lower than in UcD2k, yet almost no dead time is used. Remember that di/dt is finite, so even in the worst scenario a 20ns error at 750A/us results just in 15A excess current during 20ns. But in my circuit di/dt is shaped to be lower at the beginning of turn on process, and I use a simple but effective trick to speed up turn off of one MOSFET just when the other is starting to conduct. Source lead inductance helps a lot :)

Like all you, I had many fears at the beginning, but I found a way to synchronize an oscilloscope to the switching events with high precision (pre-trigger), and then I investigated all the processes taking place in a N-channel output stage down to the nanosecond level. I have already published waveforms a few times.
 
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...yeah, seeing ahead the sweet spot discussion of the dead time :D ....
..leading to the question if it shall optimized for low idle losses or optimized for lowest losses at max current... leading to the discussion of most fortunate ripple current in the output filter and the related component loads and of course the transfer function...
I guess we all went through all this already multiple times in the related threads. Detailed examination in real life seems to be less popular.
(Eva, your way of displaying all load situations in one screen shot is great for efficient design work. But for teaching, it would be better to show just one load situation in one screen shot, and a second load situation in a second screen shot.)

Anyway, the IPPs are looking promising, but I also dislike data sheets without specification of Qrr as a function of temperature and di/dt.
IMHO for designing class D amps the missing specification of max. dv/dt is even worse.
As long as Infineon does not specify this - my favorites will remain:
IRFB4615, IRFB4227, IRFP4668.
Erhm, yes and if I remember right there were also pretty nice Fairchild types.

P.S:
Threshold voltage of the IPP appears to be pretty low, which is more demanding for the design of the gate driver and layout.
 
Yup, the FDP42AN15A0 was the one I was formerly thinking of.
But the data sheet does also not specify Qrr as a function of di/dt.
Also max dv/dt is not specified.
Except the short comings of the specification, it could be similar to the IRFB4615.

Sorry for messing up this thread, which is about the new promising Infineon types.
Anybody out there who works for Infineon and could help to get a more detailed specification?
 
Yup, the FDP42AN15A0 was the one I was formerly thinking of.
But the data sheet does also not specify Qrr as a function of di/dt.
Also max dv/dt is not specified.
Except the short comings of the specification, it could be similar to the IRFB4615.

Sorry for messing up this thread, which is about the new promising Infineon types.
Anybody out there who works for Infineon and could help to get a more detailed specification?

I don t work for Infineon, but I know a sales person very well, she is selling CoolMos by the millions to our company and I can approach her by mail or phone (if I don t forget because of 100 things to do once in the office)...
So to sum up: We need Qrr as a function of di/dt and max dv/dt, right?
 
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